//1,先将base64转换为blob
const dataURLtoBlob = (dataurl) => {
    var arr = dataurl.split(','),
        mime = arr[0].match(/:(.*?);/)[1],
        bstr = atob(arr[1]),
        n = bstr.length,
        u8arr = new Uint8Array(n);
    while (n--) {
        u8arr[n] = bstr.charCodeAt(n);
    }
    return new Blob([u8arr], { type: mime });
}

//2,再将blob转换为file
const blobToFile = (theBlob, fileName) => {
    theBlob.lastModifiedDate = new Date();  // 文件最后的修改日期
    theBlob.name = fileName; // 文件名
    return new File([theBlob], fileName, { type: theBlob.type, lastModified: Date.now() });
}